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Silva Lusitana
Print version ISSN 0870-6352
Abstract
VIANA, Helder; FERNANDES, Paulo and ARANHA, José. Equations to Estimate the Aboveground Biomass of the Main Woody Shrub Species in the North and Center of Portugal. Silva Lus. [online]. 2013, vol.21, n.Especial, pp.99-109. ISSN 0870-6352.
The aim of this study was to develop allometric equations to estimate aboveground biomass of woody shrub species, occurring in the North-Center of Portugal, with potential interest for bioenergy utilization. Data was collected on 53 plots located in NUT III sub-regions of Tâmega, Dão-Lafões and Serra da Estrela. In each sample plot the age (t) was determined and the structural parameters of vegetation, such as height (h) and percentage of ground cover (GC%). were measured. Within an area of 10m2 the vegetation was cuted and the main species that occur in this type ecosystems, Adenocarpus sp. (adenocarpus), Cytisus sp. (broom), Erica sp. (heath), Pterospartum tridentatum (L.) Willk (carquesia) and Ulex sp. (furze) were separated and weighed in situ. In laboratory the moisture content was achieved, allowing to calculate the dry weight of the vegetation (t ha-1). Several regression equations were fitted, by the least squares method, having as independent variables the vegetation parameters (t, h, GC), individually or combined. The models were adjusted for each region and for the global data. The validation of the equation was based on the joint analysis of the coefficient of determination (R2), coefficient of determination adjusted (R2adj), standard error of the residues (syx), graphical analysis of the residues and Furnival’s index (FI) for comparison between models. Considering the heterogeneity of this vegetation the best models obtained present satisfactory quality with good predictive ability (for the global models a R2 > 0.73 was achieved, and for local models a R2 > 0.84 was obtained).
Keywords : Mediterranean shrubland; regression analysis; aboveground biomass; Dão-Lafões; Tâmega; Serra da Estrela.
